"There is a fifth dimension, beyond that which is known to man." Those words kicked off one of the most storied TV shows of all time, The Twilight Zone. TIME takes a look at some of its most memorable episodes

Nightmare at 20,000 Feet (1963)

Before he lifted off on Star Trek, the young William Shatner’s career got a boost with one of his two guest appearances on The Twilight Zone, starting with “Nightmare at 20,000 Feet.” In this episode, Shatner is Robert Wilson, a salesman taking his first flight after having a nervous breakdown, one not helped by the gremlin he keeps seeing on the wing of the plane — a gremlin only he seems to see. Terrified that the creature is going to bring down the jetliner, Shatner takes a gun from a sleeping policeman — remember, these were the pre-TSA days — and opens the plane’s exit to fire at the gremlin. Needless to say, Wilson is detained upon landing, but no one can explain the strange damage done to the fuselage of the plane.